Toolbar position issue within a position: sticky container

[serafinomb]

Hello,
I am having an issue with the toolbar position when the Editor is rendered inside a position: sticky element.

Demo: https://codesandbox.io/s/kk6p74226o

Notice how, by changing any text style after scrolling down, the toolbar moves up (by what seems to be the scroll offset from the parent container). The position gets calculated correctly when the element is not "sticky-ed".

I've done some debugging and the issue seems to be the function getSelectionRect (/src/util/index.js), which calls the getBoundingClientRect function on the selection range.
I am not quite sure why the native getBoundingClientRect function returns the wrong top value but it might have something to do with the component re-render right after a style-change.

Wrapping the getSelectionRect function call inside a requestAnimationFrame solves the issue but I am not sure it's the correct way to fix it.
Demo: https://codesandbox.io/s/j7k68l7833 (see /src/medium-draft/components/toolbar.js:85)

I would like to get some feedback before creating a PR.

[serafinomb]

Hello @brijeshb42,
have you had time to look into this? Is there anything I can do to make it easier for you to review/reproduce the issue?

Please, let me know.